CA2268489C - Adsorbent for separating halogenated aromatic compounds and separation method using it - Google Patents
Adsorbent for separating halogenated aromatic compounds and separation method using it Download PDFInfo
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- CA2268489C CA2268489C CA002268489A CA2268489A CA2268489C CA 2268489 C CA2268489 C CA 2268489C CA 002268489 A CA002268489 A CA 002268489A CA 2268489 A CA2268489 A CA 2268489A CA 2268489 C CA2268489 C CA 2268489C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/16—Alumino-silicates
- B01J20/18—Synthetic zeolitic molecular sieves
- B01J20/183—Physical conditioning without chemical treatment, e.g. drying, granulating, coating, irradiation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
- B01J20/28004—Sorbent size or size distribution, e.g. particle size
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
- B01J20/28011—Other properties, e.g. density, crush strength
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
- B01J20/28069—Pore volume, e.g. total pore volume, mesopore volume, micropore volume
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/389—Separation; Purification; Stabilisation; Use of additives by adsorption on solids
Abstract
The invention provides an adsorbing and separating agent for halogenated aromatic compounds, and an adsorbing and separating method for the compounds. Using the adsorbing and separating agent of the invention gives a high-purity, halogenated aromatic compound isomer. In the adsorbing and separating method of the invention, the adsorbent used is prevented from being deteriorated and its life can be prolonged. The adsorbent for separating halogenated aromatic compounds of the invention has a porosity o from 0.20 cc/cc to 0.37 cc/cc, a packing density of from 0.50 g/ml to 0.70 g/ml, and a grain size of from 0. 1 mm to 1. 0 mm. With the adsorbent, a halogenated aromatic compound isomer is separated and recovered; or a halogenated aromatic compound having a dissolved oxygen content of at most 15 ppm by weight is separated and recovered with an adsorbent. In the method, at least one, high-purity isomer can be efficiently separated and recovered from a mixture of halogenated aromatic compound isomers.
Description
ADSORBENT FOR SEPARATING HALOGENATED AROMATIC COMPOUNDS AND
SEPARATION METHOD USING IT
TECHNICAL FIELD
The present invention relates to an adsorbent for separating halogenated aromatic hydrocarbons and to a method of using it for separating one isomer from a mixture of halogenated aromatic isomers.
BACKGROUND OF THE INVENTION
Halogenated aromatic compounds are being of much industrial importance as inte:rmediates for medicines, agricultural chemicals, etc. At present, these intermediates are required to have much higher purity. Except for monohalogenated benzenes, aromatic compounds with two or more substituents each have different isomers. For separating the mixture of those isomers into individual ones through ordinary industrial distillation, an ultra-precision distillation device is needed, since the difference in the boiling point between the isomers is small. However, at present, it is still extremely difficult to obtain high-purity products of a single isomer on an industrial scale. In addition, some types of halogenated aromatic compounds could not be separated into individual isomers through distillation. Recently, for separating a mixture of isomers that have heretofore been difficult or impossible to separate into individual ones, methods of adsorbing separation have been developed. For example, JP-A 57-91933 and 58-131923 disclose a method of separating a single isomer from a mixture of chlorotoluene isomers through adsorption. Japanese Patent Application No.
9-335225 discloses a method of separating a single isomer from a mixture of chloroethylbenzene isomers through adsorption.
JP-A 52-62229, 53-105434, 58-131924, 58-150524, 62-175433 and 4-330025 disclose a method of separating a single isomer from a mixture of dichlorobenzene isamers. JP-A 59-199642, 60-42340, 5-70383, 58-137795 and 3-20232 disclose a method of separating a mixture of dichlorotoluene isomers. JP-B 4-46933 discloses a process comprising removing HC1 and water, which are formed in isomerization of a halogenated benzene derivative, through distillation, followed by separating a specific single isomer from the mixture of the resulting isomers by the use of an adsorbing and separating agenit of zeolite.
SUMMARY OF THE INVENTION
Increasing the purity of the single isomer to be separated in those adsorbing separation niethods and increasing the separation efficiency therein is an extremely important theme to the industrial effect. However, the methods mentioned above are not satisfactory with respect to the purity of the single isomer separated therein.
SEPARATION METHOD USING IT
TECHNICAL FIELD
The present invention relates to an adsorbent for separating halogenated aromatic hydrocarbons and to a method of using it for separating one isomer from a mixture of halogenated aromatic isomers.
BACKGROUND OF THE INVENTION
Halogenated aromatic compounds are being of much industrial importance as inte:rmediates for medicines, agricultural chemicals, etc. At present, these intermediates are required to have much higher purity. Except for monohalogenated benzenes, aromatic compounds with two or more substituents each have different isomers. For separating the mixture of those isomers into individual ones through ordinary industrial distillation, an ultra-precision distillation device is needed, since the difference in the boiling point between the isomers is small. However, at present, it is still extremely difficult to obtain high-purity products of a single isomer on an industrial scale. In addition, some types of halogenated aromatic compounds could not be separated into individual isomers through distillation. Recently, for separating a mixture of isomers that have heretofore been difficult or impossible to separate into individual ones, methods of adsorbing separation have been developed. For example, JP-A 57-91933 and 58-131923 disclose a method of separating a single isomer from a mixture of chlorotoluene isomers through adsorption. Japanese Patent Application No.
9-335225 discloses a method of separating a single isomer from a mixture of chloroethylbenzene isomers through adsorption.
JP-A 52-62229, 53-105434, 58-131924, 58-150524, 62-175433 and 4-330025 disclose a method of separating a single isomer from a mixture of dichlorobenzene isamers. JP-A 59-199642, 60-42340, 5-70383, 58-137795 and 3-20232 disclose a method of separating a mixture of dichlorotoluene isomers. JP-B 4-46933 discloses a process comprising removing HC1 and water, which are formed in isomerization of a halogenated benzene derivative, through distillation, followed by separating a specific single isomer from the mixture of the resulting isomers by the use of an adsorbing and separating agenit of zeolite.
SUMMARY OF THE INVENTION
Increasing the purity of the single isomer to be separated in those adsorbing separation niethods and increasing the separation efficiency therein is an extremely important theme to the industrial effect. However, the methods mentioned above are not satisfactory with respect to the purity of the single isomer separated therein.
In the method of using an adsorbing and separating agent that comprises zeolite for separating a single isomer from a mixture of halogenated aromatic compound isomers, the capabilities of the adsorbing and separating agent being used are lowered with the lapse of time. In the method, therefore, the adsorbing and separating agent being used must be exchanged for a fresh one or must be regenerated through firing or the like. Therefore, prolonging the life of the agent and prolonging the regeneration cycle:for the agent is extremely advantageous to the industrial effect. However, the conventional techniques are unsatisfactory with respect to the prolongation of the life of the aqent and to the prolongation of the regeneration cycle for it.
The invention is to solve the problems noted above, and to provide an efficient method for separating halogenated aromatic compound isomers.
In order to solve these proble:ms, we, the present inventors have assiduously studied the capabilities of adsorbents for improving them. Adsorbents consist essentially of zeolite.
Zeolite includes natural zeolite and synthetic zeolite, of which synthetic zeolite is especially preferably used.
Synthetic zeolite is generally in the form of powder. For using zeolite as industrial adsorbents, it must be shaped.
Specifically, zeolite adsorbents are generally in the form of shaped articles. Having noticedt:he shaped articles of zeolite as adsorbents, we have investigated the factors that may govern the capabilities of zeolite to adsorb and separate halogenated aromatic compounds. As a result, we have found that the packing density of the adsorbent, the porosity of the adsorbent and the grain size of the adsorbent are important factors.
The packing density of an adsorbent depends on the porosity thereof, the shape thereof, etc. An adsorbent having a higher packing density is preferred, since its amount capable of being filled in a unit volume increases and since a larger amount of the adsorbent could be filled in an adsorbent tower. However, for an adsorbent having a too high packing density, it has been found that its adsorbing and separating capabilities are lowered.
The porosity of an adsorbent is caused by the macro pores existing in the adsorbent. An adsorbent having a too high porosity is unfavorable, since its packing density is lowered.
Contrary to this, for an adsorbent having a too low porosity, the volume of macro pores existirig therein is too small. As a result, it has been found that, when a halogenated aromatic compound is applied to the adsorbent of zeolite of that type, it is prevented from being diffused in the adsorbent grains before it reaches the pores through which the compound is adsorbed by the adsorbent, zeolite, and therefore the adsorbing and separating capabilities of t:he adsorbent are poor.
The invention is to solve the problems noted above, and to provide an efficient method for separating halogenated aromatic compound isomers.
In order to solve these proble:ms, we, the present inventors have assiduously studied the capabilities of adsorbents for improving them. Adsorbents consist essentially of zeolite.
Zeolite includes natural zeolite and synthetic zeolite, of which synthetic zeolite is especially preferably used.
Synthetic zeolite is generally in the form of powder. For using zeolite as industrial adsorbents, it must be shaped.
Specifically, zeolite adsorbents are generally in the form of shaped articles. Having noticedt:he shaped articles of zeolite as adsorbents, we have investigated the factors that may govern the capabilities of zeolite to adsorb and separate halogenated aromatic compounds. As a result, we have found that the packing density of the adsorbent, the porosity of the adsorbent and the grain size of the adsorbent are important factors.
The packing density of an adsorbent depends on the porosity thereof, the shape thereof, etc. An adsorbent having a higher packing density is preferred, since its amount capable of being filled in a unit volume increases and since a larger amount of the adsorbent could be filled in an adsorbent tower. However, for an adsorbent having a too high packing density, it has been found that its adsorbing and separating capabilities are lowered.
The porosity of an adsorbent is caused by the macro pores existing in the adsorbent. An adsorbent having a too high porosity is unfavorable, since its packing density is lowered.
Contrary to this, for an adsorbent having a too low porosity, the volume of macro pores existirig therein is too small. As a result, it has been found that, when a halogenated aromatic compound is applied to the adsorbent of zeolite of that type, it is prevented from being diffused in the adsorbent grains before it reaches the pores through which the compound is adsorbed by the adsorbent, zeolite, and therefore the adsorbing and separating capabilities of t:he adsorbent are poor.
On the other hand, it has been found that a shaped adsorbent comprising smaller grains could have higher adsorbing and separating capabilities. It is believed that, in zeolite adsorbent grains having a small grain size, the pathway through which a halogenated aromatic compound to be adsorbed by the grains are diffused into the pores of the zeolite grains will be shortened, whereby the compound could be rapidly adsorbed by the grains. It is considered that the diffusion of halogenated aromatic compounds into adsorbent grains will be much influenced by the grain sizE: of the grains, as compared with that of halogen-free aromati<: hydrocarbons. This will be probably related to the fact that halogens, for example, chlorine and bromine have a large ionic radius or a large atomic weight. However, adsorbentgrainshaving a too small grain size are unfavorable, since they will cause the increase in pressure loss.
We, the present inventors have studied production methods for aromatic compounds, and, as a result, have found that using a halogenated aromatic compound having a dissolved oxygen content of at most 15 ppm by weight prevents the deterioration of an adsorbing and separating agent and prolongs the life of the agent, and that the halogenated aromatic compound can be efficiently separated.
Specifically, the invention provides an adsorbent for separating a halogenated aroniatic compound, which is characterized by having a packing density of from 0.50 g/ml to 0.70 g/ml, a porosity of from 0.2 to 0.37 cc/cc, and a grain size of from 0.1 mm to 1.0 mm; a method of using the adsorbent for separating at least one ha1-ogenated aromatic compound isomer from a mixture of halogenated aromatic compound isomers;
and a method for separating at lei3st one halogenated aromatic compound isomer, which comprise:s contacting a mixture of halogenated aromatic compound isoniershaving a dissolved oxygen content of at most 15 ppm by weight with an adsorbent for separating halogenated aromatic compounds.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic view showing a device for measuring the packing density of an adsorbent.
Fig. 2 is a schematic view showing the adsorption and separation process of one embodiment of the invention in a simulated-moving bed line.
Fig. 3 is a graph showing the pore volume distribution of the adsorbents in Example 1 and Example 2.
Fig. 4 is a graph showing the adsorbing and separating capabilities of the adsorbents f'or a CEB isomer mixture in Example 1 and Comparative Example 1.
Fig. 5 is a graph showing the adsorbing and separating capabilities of the adsorbents f'or a DCB isomer mixture in Examples 2, 3 and 4.
Fig. 6 is a graph showing the relationship between the amount of the isomer mixture processed and the adsorptive selectivity of the single isomer separated in Example 5 and Comparative Example 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The essential component in the adsorbent of the invention is synthetic zeolite. Examples of the zeolite usable herein include faujasite-type zeolite, MFI-type zeolite and beta-type zeolite. Most preferred is faujasite-type zeolite.
Faujasite-type zeolite is a crystalline aluminosilicate to be represented by the following gene:ral formula in terms of the molar ratio of the oxides constiituting it:
MZinO = AlZO3 = xSiOZ = yH2O
wherein M represents a metal ion or a hydrogen ion; n represents the valence of the metal ion or the hydrogen ion; x represents a molar ratio of silica/alumina. One with x of smaller than 3 is referred to as X-type zeolite, and one with x or 3 or more is referred to as Y-type zeolite. In the formula, y varies depending on the degree of hydration.
Synthetic zeolite is genera]-ly obtained in the form of powder. For shaping the powder, f'or example, employed is any method of kneading, rolling or compression. In the invention, a kneading method is preferred. In shaping the powder, a binder is often used for increasing the mechanical strength and the packing density of the shaped articles. As the binder, preferred are alumina, bentonite, kaolin, etc. Depending on the intended mechanical strength and packing density of the shaped articles, the amount of the binder to be used may fall between 5 and 40 % by weight, but preferably between 10 and 20 %
by weight. In view of the zeolite content of the shaped articles, it is desirable that the amount: of the binder is smaller.
However, the uppermost limit ancl the lowermost limit of the amount of the binder to be used sY:Lall be determined, depending on the type of the binder and the intended mechanical strength of the shaped articles. The amount of the binder also depends on the crystal structure and the crystal morphology of zeolite.
For shaping zeolite in a kneading method, zeolite powder, binder, water and optionally surfactant that is to improve the shapability are well kneaded. The surfactant to be optionally used herein includes, for example, anionic surfactants ( e. g., triethanolamine oleate, sodium oleate), cationic surfactants (e.g., N-cetyl-N-ethyl morpholin_Lum Et sulfate e.g. trade-mark "Atlas G-251" ), nonionic surfactants (e.g. , oleic acid, sorbitan trioleate e.g. trade-mark "Span 85", sorbitan monooleate e.g.
trade-mark"Span 8 0", sorbitan monolaurate e.g. trade-mark "Span 20", polyoxyethylene sorbitan m(Dnostearate e.g. trade-mark "Tween 60", polyoxyethylene sorbitan monooleate e.g. trade-mark "Tween 80", polyoxyethylene sortiitan monolaurate e.g. trade-mark "Tween 20").
The kneaded mixture is extruded through an extruder, for which the screen mesh is suitably selected to control the grain size of the intended adsorbent grains. The extruded adsorbent grains are then processed in a rounding machine (Marumerizer), in which their length is controlled or they are rounded.
Through the rounding operation, the packing density of the adsorbent grains ane the porosity could be controlled in some degree.
The shaped adsorbent is thE;n dried for removing water therefrom. The drying temperature may generally fall between 50 and 200 C. After having been dried, this is then calcined to thereby have an increased mechanical strength. The calcination temperature generally falls between 350 and 700 C.
The adsorbent thus having been calcined to have an increased mechanical strength is thereafter optionally subjected to cation exchange treatment, depending on the type of the halogenated aromatic compouind to be treated with it. For the ion exchange treatment, employable is any and every cation generally employed in the art.
The packing density of the adsorbent may vary in some degree, depending on the measuririg method used. The packing density of the adsorbent of the invention is measured according to the method mentioned below.
(1) The empty weight of a measuring container is measured, and this is referred to as (A). The container is prepared by cutting a 250-m1 messcylinder having an outer diameter of 40 mm~, at a height of 200 mmH from its bottom, and its volume, V, is previously determined with water.
(2) The measuring equipment is set as in Fig. 1.
(3) About 300 ml of a calcined adsorbent (sample) is taken in a glass beaker.
(4) The distance between the top of the measuring container C and the top of the funnel F is settled to be 200 mm, and the sample in the glass beaker is fed into the funnel F, while being dropped into the container C through the funnel F to heap up.
(Note: The sample is dropped into the center of the container C, messcylinder, and the measuring equipment must not be moved during the measurement.) (5) After the sample has been dropped into the container C, its heaped part is gently scarped off with a scale to be flat.
We, the present inventors have studied production methods for aromatic compounds, and, as a result, have found that using a halogenated aromatic compound having a dissolved oxygen content of at most 15 ppm by weight prevents the deterioration of an adsorbing and separating agent and prolongs the life of the agent, and that the halogenated aromatic compound can be efficiently separated.
Specifically, the invention provides an adsorbent for separating a halogenated aroniatic compound, which is characterized by having a packing density of from 0.50 g/ml to 0.70 g/ml, a porosity of from 0.2 to 0.37 cc/cc, and a grain size of from 0.1 mm to 1.0 mm; a method of using the adsorbent for separating at least one ha1-ogenated aromatic compound isomer from a mixture of halogenated aromatic compound isomers;
and a method for separating at lei3st one halogenated aromatic compound isomer, which comprise:s contacting a mixture of halogenated aromatic compound isoniershaving a dissolved oxygen content of at most 15 ppm by weight with an adsorbent for separating halogenated aromatic compounds.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic view showing a device for measuring the packing density of an adsorbent.
Fig. 2 is a schematic view showing the adsorption and separation process of one embodiment of the invention in a simulated-moving bed line.
Fig. 3 is a graph showing the pore volume distribution of the adsorbents in Example 1 and Example 2.
Fig. 4 is a graph showing the adsorbing and separating capabilities of the adsorbents f'or a CEB isomer mixture in Example 1 and Comparative Example 1.
Fig. 5 is a graph showing the adsorbing and separating capabilities of the adsorbents f'or a DCB isomer mixture in Examples 2, 3 and 4.
Fig. 6 is a graph showing the relationship between the amount of the isomer mixture processed and the adsorptive selectivity of the single isomer separated in Example 5 and Comparative Example 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The essential component in the adsorbent of the invention is synthetic zeolite. Examples of the zeolite usable herein include faujasite-type zeolite, MFI-type zeolite and beta-type zeolite. Most preferred is faujasite-type zeolite.
Faujasite-type zeolite is a crystalline aluminosilicate to be represented by the following gene:ral formula in terms of the molar ratio of the oxides constiituting it:
MZinO = AlZO3 = xSiOZ = yH2O
wherein M represents a metal ion or a hydrogen ion; n represents the valence of the metal ion or the hydrogen ion; x represents a molar ratio of silica/alumina. One with x of smaller than 3 is referred to as X-type zeolite, and one with x or 3 or more is referred to as Y-type zeolite. In the formula, y varies depending on the degree of hydration.
Synthetic zeolite is genera]-ly obtained in the form of powder. For shaping the powder, f'or example, employed is any method of kneading, rolling or compression. In the invention, a kneading method is preferred. In shaping the powder, a binder is often used for increasing the mechanical strength and the packing density of the shaped articles. As the binder, preferred are alumina, bentonite, kaolin, etc. Depending on the intended mechanical strength and packing density of the shaped articles, the amount of the binder to be used may fall between 5 and 40 % by weight, but preferably between 10 and 20 %
by weight. In view of the zeolite content of the shaped articles, it is desirable that the amount: of the binder is smaller.
However, the uppermost limit ancl the lowermost limit of the amount of the binder to be used sY:Lall be determined, depending on the type of the binder and the intended mechanical strength of the shaped articles. The amount of the binder also depends on the crystal structure and the crystal morphology of zeolite.
For shaping zeolite in a kneading method, zeolite powder, binder, water and optionally surfactant that is to improve the shapability are well kneaded. The surfactant to be optionally used herein includes, for example, anionic surfactants ( e. g., triethanolamine oleate, sodium oleate), cationic surfactants (e.g., N-cetyl-N-ethyl morpholin_Lum Et sulfate e.g. trade-mark "Atlas G-251" ), nonionic surfactants (e.g. , oleic acid, sorbitan trioleate e.g. trade-mark "Span 85", sorbitan monooleate e.g.
trade-mark"Span 8 0", sorbitan monolaurate e.g. trade-mark "Span 20", polyoxyethylene sorbitan m(Dnostearate e.g. trade-mark "Tween 60", polyoxyethylene sorbitan monooleate e.g. trade-mark "Tween 80", polyoxyethylene sortiitan monolaurate e.g. trade-mark "Tween 20").
The kneaded mixture is extruded through an extruder, for which the screen mesh is suitably selected to control the grain size of the intended adsorbent grains. The extruded adsorbent grains are then processed in a rounding machine (Marumerizer), in which their length is controlled or they are rounded.
Through the rounding operation, the packing density of the adsorbent grains ane the porosity could be controlled in some degree.
The shaped adsorbent is thE;n dried for removing water therefrom. The drying temperature may generally fall between 50 and 200 C. After having been dried, this is then calcined to thereby have an increased mechanical strength. The calcination temperature generally falls between 350 and 700 C.
The adsorbent thus having been calcined to have an increased mechanical strength is thereafter optionally subjected to cation exchange treatment, depending on the type of the halogenated aromatic compouind to be treated with it. For the ion exchange treatment, employable is any and every cation generally employed in the art.
The packing density of the adsorbent may vary in some degree, depending on the measuririg method used. The packing density of the adsorbent of the invention is measured according to the method mentioned below.
(1) The empty weight of a measuring container is measured, and this is referred to as (A). The container is prepared by cutting a 250-m1 messcylinder having an outer diameter of 40 mm~, at a height of 200 mmH from its bottom, and its volume, V, is previously determined with water.
(2) The measuring equipment is set as in Fig. 1.
(3) About 300 ml of a calcined adsorbent (sample) is taken in a glass beaker.
(4) The distance between the top of the measuring container C and the top of the funnel F is settled to be 200 mm, and the sample in the glass beaker is fed into the funnel F, while being dropped into the container C through the funnel F to heap up.
(Note: The sample is dropped into the center of the container C, messcylinder, and the measuring equipment must not be moved during the measurement.) (5) After the sample has been dropped into the container C, its heaped part is gently scarped off with a scale to be flat.
(6) The weight of the container C with the sample therein is measured, and this is referred to as (B).
(Note: As the sample is highly hygroscopic, the operation of (1) to (6) must be effected rapidly).
(Note: As the sample is highly hygroscopic, the operation of (1) to (6) must be effected rapidly).
(7) The measurement is repeated twice, and the average value is obtained.
(8) A 30-m1 ceramic crucible that has been previously calcined at 500 C for 1 hour is weighed. About 2 g of the same sample as above is accurately weighed and put into the crucible, which is then calcined at 500 C for 1 hour. This is cooled in a desiccator for about 15 minutes. After having reached room temperature, this is weighed. From the thus-weighed dry weight of the sample, calculated is the water content (% by weight) of the non-dried sample.
(9) The packing density ( ABD ) of the sample is calculated according to the following equation:
B - A 100 - water content ABD (g/ml) = x (1-wherein;
A indicates the weight of the empty container (g), B indicates the weight of the sample ( adsorbent )+ A (g), and V indicates the volume of tY:ie measuring container (ml).
An adsorbent having a higher packing density is preferred, since its amount capable of being filled in a unit volume increases. However, an adsorben't having a too high packing density is unfavorable, since its adsorbing and separating capabilities for halogenated aromatic compounds are poor.
The porosity of an adsorbent: can be measured with ease, according to a method of mercury penetration, for which is used a porosimeter. Concretely, the porosity of the adsorbent of the invention is measured in the manner mentioned below.
The adsorbent to be measured is put in an electric furnace, calcined therein at 500 C for 2 hours, and then cooled in a desiccator to reach room temperature. This is put in a sample cell, and is thereafter filled with mercury in vacuum. Then, this is set in a porosimeter device. Pressure is applied thereto, whereupon the volume of miercury to be penetrated into the pores of the adsorbent grains is electrically detected.
Thus is obtained the relationship between the pressure Pm[psi]
and the pore volume[cc]. This measurement is repeated under different pressures. The pressure: Pm is converted into the pore radius, r, according to the following equation (1):
r = -2?'cos8/P --- (1) wherein;
r indicates the radius of pores into which mercury penetrates under a pressure P, [A], P indicates a pressure, P=Pm[psi]X6.89476X103[N/m-m], r indicates the surface tension of mercury, 0.484[N/m], and 0 indicates the contact angle of mercury to the sample (adsorbent), 141.'3[o ].
The volume of the adsorbent grains is obtained as follows:
The adsorbent grains to be measured are put into a sample cell.
The volume as expelled by the adsorbent grains to which is added mercury in vacuum, and the pore volume of the grains having a pore diameter of up to 3 um to w:hich is added mercury under pressure are summed up, and the total is the volume of the adsorbent grains. The pore volunie is the accumulated volume of mercury as penetrated into the qrains having a pore diameter of from 3}un to 10 nm. Accordingly, the porosity ( cc/cc ) of the adsorbent grains is defined as follows:
(pore volume (cc)) Porosity (cc/cc) = --- (2) (adsorbent g:rain volume (cc) Adsorbent grains having a larger porosity are preferred, since a halogenated aromatic compound could more easily diffuse inside the grains. However, too large grains are unfavorable, since the packing density of the adsorbent is lowered.
Preferably, the porosity of the adsorbent grains falls between 0.20 and 0.37 cc/cc, more preferably between 0.25 and 0.35 cc/cc.
The grain size of the adsorbent grains can be easily measured with a scale or a scale equ_Lpped with a magnifying glass.
At least any 10 adsorbent grains are measured for their grain size, and the data are averaged. The resulting mean value is the grain size of the grains. In the invention, the grain size of the adsorbent grains preferably falls between 0.1 and 1.0 mm, more preferably between 0.2 and 0.8 mm. Adsorbent grains having a smaller grain size are preferred, since the pathway in each grain through which the adsorbed molecules diffuse in the grains is shorter. However, too small grains are unfavorable, since they cause the increase in pressure loss, and since their industrial production is not economical.
The halogen to be in the halogenated aromatic compounds to which the invention is directed includesfluorine, chlorine, bromine and iodine. Of those, favorable to the invention are chlorine and bromine, and more favorable thereto is chlorine.
It is also desirable that the hal-ogenated aromatic compounds have at least one alkyl group. The alkyl group preferably has from 1 to 4 carbon atoms, and more preferred are methyl group, ethyl group and propyl group.
Specific examples of the ha]-ogenated aromatic compounds include fluorotoluene, chlorotoluene, bromotoluene, dichlorobenzene, dibromobenzene, fluorochlorobenzene, chlorobromobenzene, trichlorobenzene, dichlorofluorobenzene, dichlorobromobenzene, dibromochlorobenzene, dichlorotoluene, dibromotoluene, chloroxylene, bromoxylene, chloroethylbenzene, bromoethylbenzene, chlorocumene, chloropropylbenzene, bromocumene, bromopropylbenzene, chlorobutylbenzene, bromobutylbenzene, etc.
In the invention, when the dissolved oxygen content of the halogenated aromatic compound to be processed is not higher than 15 ppm by weight, the adsorbent used for the compound could be prevented from being deteriorated. Smaller dissolved oxygen content is better. Preferably, t:he dissolved oxygen content is at most 5 ppm by weight, more preferably at most 1 ppm by weight.
The dissolved oxygen conter.it of the aromatic compound could be measured with a Beckmari dissolved oxygen meter, a polarographic dissolved oxygen meter or the like.
To reduce the dissolved oxygen content of the aromatic compound to be at most 15 ppm by weight, for example, employable is any treatment of radiation, degassing, distillation, nitrogen sealing or the like.
In the invention, the radiation treatment is to contact a liquid of a dissolved oxygen-containing aromatic compound with an inert gas such as NZ or the like, thereby removing the dissolved oxygen from the aromatic compound. For the radiation, for example, NZ may be directly lbubbled into a liquid of an aromatic compound as put in a tank, or, alternatively, N2 may be contacted with a liquid of an aromatic compound in a countercurrent flow in a plate coJ-umn or a packed column. The pressure for the operation may be any of normal pressure, elevated pressure or reduced pressure. Regarding the temperature for the operation, the operation is generally effected at a temperature at which the aromatic compound to be processed could be in a liquid phase.
The degassing treatment includes, for example, a method of reducing the pressure in a tank as filled with a dissolved oxygen-containing aromatic compound, by the use a vacuum pump or the like; and a method of reducing the pressure in a plate column or a packed column as filled with a liquid of a dissolved oxygen-having aromatic compoundtothereby remove the dissolved oxygen from the compound. The pr-essure for the operation may be any of vacuum to normal pressure, but a lower pressure is preferred. Regarding the temperature for the operation, the operation is generally effected at a temperature at which the aromatic compound to be processed could be in a liquid phase.
The distillation treatment may be effected in any ordinary manner. For this, the distillation tower may be any of a plate column, a packed column or the like, and the pressure may be any of normal pressure, elevated pressure or reduced pressure.
The nitrogen sealing treatment is to put a dissolved oxygen-containing aromatic compound into a nitrogen-sealed container, for example, tank, before the compound is subjected to isomerization or adsorbing separation, so that the dissolved oxygen is removed from the compound through vapor-liquid equilibration.
If a halogenated aromatic compound to be subjected to adsorbing separation contains dissolved oxygen, the dissolved oxygen in the compound will form an oxygen-containing compound.
Since the resulting oxygen-containing compound has strong polarity, and is therefore strongly adsorbed by the adsorbing and separating agent, whereby tYae adsorbing and separating capabilities of the agent are much lowered. Therefore, reducing the dissolved oxygen content of the halogenated aromatic compound is effective for preventing the deterioration of the adsorbing and separating aclent, and it is believed that the regeneration cycle for the agent could thereby be prolonged.
The technique of adsorbing and separating a single isomer from a mixture of halogenated aromatic compound isomers according to the invention may be attained in so-called partitioning chromatography, in partitioning adsorption using a simulated-moving bed line comprising a series of partitioning chromatography columns. In the simulated-moving bed line, the most easily adsorbable substance is collected in the extract flow, while the most hardly adsorbable substance is collected in the raffinate flow.
The continuous adsorbing and separating technique using the simulated-moving bed line basically comprises adsorption, concentration, desorption and desorbent recovery, which are continuously repeated in that order. One example of a method of adsorbing and separating a mixture of chloroethylbenzene (hereinafter referred to as "CEB") isomers is mentioned below, in which m-CEB is adsorbed by the adsorbent used.
Fig. 2 shows a schematic view showing the adsorption and separation process according to the simulated-moving bed line. As in Fig. 2, adsorption chambers 1 to 12 all filled with an adsorbent are continuously connected with each other, through which the isomer mixture to be separated is circulated.
(1) Adsorption:
A mixture of CEB isomers from feed line 15 is contacted with an adsorbent, and a strongly adsorbable component, m-CEB is selectively adsorbed by the adsorbent, while the other weakly adsorbable components, o- and p-CEBs are recovered along with the desorbent in the form of a raffinate flow of raffinate line 16 that will be mentioned below.
(2) Concentration:
The adsorbent that has adsorbed the strongly adsorbable component, m-CEB is then contacted with a part of the extract that will be mentioned below, and the weakly adsorbable components remaining on the adsorbent are removed, whereby the strongly adsorbable component is concentrated.
(3) Desorption:
The adsorbent thus having the concentrated, strongly adsorbable component, m-CEB is contacted with a desorbent from desorption line 13, whereby the strongly adsorbable component is removed from the adsorbent, and recovered along with the desorbent in the form of an extract flow of extract line 14.
(4) Desorbent Recovery:
The adsorbent thus having adsorbed substantially only the desorbent is contacted with a part of the raffinate flow, and a part of the desorbent having been adsorbed by the adsorbent is recovered in the form of a desorbent recovery flow of desorption recovery line 17.
The adsorbing and separating operation for a halogenated aromatic compound is preferably effected in a liquid phase. A higher operation temperature is more preferred for higher diffusion rate of the compound being processed. Contrary to this, however, a lower operation temperature is more preferred for better adsorptive selectivity of the adsorbent used.
Because of the contradictory temperature-dependent factors, the operation temperature will be preferably between 50 and 2000 C.
EXAMPLES
Example 1:
1.2 kg (dry weight) of Na-X zeolite powder (from Toso) having a molar ratio SiOZ/A1z03 of 2.5, 0.96 kg of alumina sol ( from Nissan Chemical, having an A1203 content of 10 % by weight) and alumina gel (from Shokubai Kasei, having an A12O3 content of 75 % by weight) were mixed in a kneader (from Fuji Pawdal, Model KDHJ-10), and kneaded with a suitable amount of water added thereto, for about 1 hour. The resulting paste was extruded out through an extrude:r (from Fuji Pawdal, Model EXDS-60) equipped with a 0.3 mm-mesh screen, into pellets.
In order to round them and to increase their packing density, the resulting pellets were processed in a rounding machine (Marumerizer, Model QJ-230 from Fuji Pawdal), at a revolution of 850 rpm for 3 minutes.
Next, these were dried overnight at about 120 C. After having been dried, these were classified through a 80-mesh sieve to remove fine grains and through a 48-mesh sieve to remove coarse grains. The thus-classified grains were then calcined at 500 C for 2 hours.
The diameter of the adsorbent grains was measured with a scale equipped with a magnifying glass, and it was 0.3 mm. The length of the grains varied from about 0.3 mm to about 0.6 mm.
The packing density of the adsorbent was 0.54 g/ml. The pore volume of the adsorbent grains was measured, and the data are shown in Fig. 3. The adsorbent had a porosity of 0.27 cc/cc.
The adsorbent was filled into 12 columns each having a size of 4.6 mm~ x 1 m. Of those columns, four were set in a desorption zone, three were in a concentration zone, three were in an adsorption zone, and two were in a desorbent recovery zone in a simulated-moving bed line. A mixture of chloroethylbenzene ( CEB ) isomers was applied to the s_Lmulated-moving bed line, and the adsorbing and separating capabilities of the adsorbent in the line were checked. The starting CEB isomer mixture applied had a composition of o-CEB/m-CE13/p-CEB = 33/47/20. As the desorbent, used was xylene. The operation temperature was 130 C. The capabilities curve is shown in Fig. 4.
Comparative Example 1:
An adsorbent was prepared in the same manner as in Example 1, except that the extruded grains were not rounded with Marumerizer. The packing density of the adsorbent prepared herein was 0.49 g/ml. The pore volume of the adsorbent was measured, and the data are shown in Fig. 3. The adsorbent had a porosity of 0.38 cc/cc.
Using the adsorbent, the CEB isomer mixture was processed in the same manner as in Example 1 to check the adsorbing and separating capabilities of the adsorbent. The data obtained are shown in Fig. 4.
The data in Fig. 4 indicate that the most strongly adsorbable m-CEB was recovered in the extract flow and its purity in the flow was high. In addition, the data indicate that the adsorbent giving a higher ratio of m-CEB/ECEB (total of o-, m- and p-CEBs) in the extract flow and giving a lower ratio of m-CEB/FCEB in the raffineite flow has better adsorbing and separating capabilities. Obviously, it is known that the adsorbent having an increased packing density of 0. 54 mg/ml from 0.49 mg/ml and having a decreased porosity of 0.27 cc/cc from 0.38 cc/cc has better adsorbing ELnd separating capabilities.
Example 2:
An adsorbent paste was prepared in the same manner as in Example 1, except that Na-Y zeolite powder (from Toso) having a molar ratio Si02/A1Z03 of 5.5 was used herein, and this was extruded out through an extruder equipped with a 0.3 mm-mesh screen into adsorbent pellets.
In order to round them and to increase their packing density, the resulting pellets were processed in a rounding machine, Marumerizer, at a revolution of 850 rpm for 3 minutes.
Next, these were dried overriight at about 120 C. After having been dried, these were classified through a 80-mesh sieve to remove fine grains and through a 48-mesh sieve to remove coarse grains. The thus-classified grains were then calcined at 500 C for 2 hours.
The calcined grains were treated in an aqueous solution containing 5 % by weight of KNO3, at a liquid/solid ratio (L/S) of 4 ml/g at about 80 C for 1 hour. Next, these were washed with distilled water at a liquid/solid ratio of 4. The K ion exchanging treatment followed by washing with water was repeated 8 times. After this treatment, the grains were washed with distilled water at a liquid/solid ratio of 8, which was repeated 5 times.
Next, these grains were further subjected to ion exchanging treatment with an aqueous solution of 55 g of PbNO3 dissolved in one liter of water, at room temperature for about 1 hour, and then washed with distilled water at a liquid/solid ratio of 4. The washing was repe:ated 5 times.
The thus-prepared adsorbent was dried overnight at about 120 C, and then calcined at 500 c; for 2 hours.
The diameter of the adsorbent grains was measured with a scale equipped with a magnifying glass, and it was 0.3 mm. The length of the grains varied from about 0.3 mm to about 0.6 mm.
The packing density of the adsorbent was 0.65 g/ml. The pore diameter of the adsorbent grains was measured, and the data are shown in Fig. 3, which indicates the pore diameter distribution.
The adsorbent had a porosity of 0.26 cc/cc.
The adsorbent was filled inta 12 columns each having a size of 4. 6 mm~ x 1 m. Of those columns, four were set in a desorption zone, three were in a concentra"tion zone, three were in an adsorption zone, and two were in a desorbent recovery zone in a simulated-moving bed line. A mixture of dichlorobenzene (hereinafter referred to as "DCB") isomers was applied to the simulated-moving bed line, and the adsorbing and separating capabilities of the adsorbent in the line were checked. The starting DCB isomer mixture applied had a composition of o-DCB/m-DCB/p-DCB = 37/40/23. As the desorbent, used was dichlorotoluene. The operation temperature was 130 C. The capabilities curve is shown in Fig. 5.
Example 3:
An adsorbent was prepared in the same manner as in Example 2, except that the rounding treatment with Marumerizer was effected at a revolution of 400 rpin for 1 minutes. The packing density of the adsorbent was 0.60 (3/ml. The pore volume of the adsorbent grains was measured, and the data are shown in Fig.
3. The adsorbent had a porosity of 0.35 cc/cc.
The DCB adsorbing and separating capabilities of the adsorbent were checked in the samE; manner as in Example 2, and the data are shown in Fig. 5.
Example 4:
An adsorbent was prepared in the same manner as in Example 2, except that the extruder was equipped with a 1.2 mm-mesh screen and that a 24-mesh sieve and a 10-mesh sieve were used for the grain classification.
The diameter of the adsorbent grains was measured with a scale equipped with a magnifying glass, and it was 1. 2 mm. The length of the grains was 2.0 mm. The packing density of the adsorbent was 0.67 g/ml. The adsorbent had a porosity of 0.25 cc/cc.
The DCB adsorbing and separating capabilities of the adsorbent were checked in the same manner as in Example 2, and the data are shown in Fig. 5.
Fig. 5 indicates that the most weakly adsorbable m-DCB was recovered in the raffinate flow aizd its purity in the flow was high. In addition, the data in Fig. 5 indicate that the adsorbent giving a higher ratio of m-DCB/EDCB (total of o-, m-and p-DCBs) in the raffinate flow and giving a lower ratio of m-DCB/EDCB in the extract flow has better adsorbing and separating capabilities. Obviously, it is known that the adsorbents in Examples 2 and 3 have better adsorbing and separating capabilities.
Example 5:
An adsorbent for separating 2,4-dichlorotoluene (hereinafter referred to as DCT) was prepared according to the method of Example 3 in JP-A 5-70383. This adsorbing and separating agent is of X-type zeo:Lite containing, as cations, sodium and strontium ions. This was calcined at 500 C for 2 hours, and filled in a stainless steel column having an inner diameter of 4.6 mm and a length of 1 m. While m-xylene having been disoxidated through nitrogen bubbling (this m-xylene had a dissolved oxygen content of nearly 0 ppm, as measured with a polarographic dissolved oxygen meter) was introduced into the column at a constant flow rate, a small amount of a mixture of 2,4-, 2,5- and 2,6-DCTs and n-nonane that had been disoxidated in the same manner of nitrogen biubbling (this mixture had a dissolved oxygen content of nearly 0 ppm, as measured with a polarographic dissolved oxygen met:er) was applied to the column for an instant, and the liquid flowing out through the outlet was sampled at predetermined intervals, and analyzed for its composition through gas chromatography. All the starting liquid used herein were previously dewatered through a molecular sieve. Time-dependent]Ly plotting the data of the analysis gives the concentration;peak of each component. The selectivity of the adsorbing and. separating agent could be represented by the ratio of the difference in the retention time (hereinafter referred to as "RT") between one isomer and n-nonane to that in the same between another isomer and n-nonane, as in the equation mentioned below. In general, adsorbents having a larger value for the selectivity to be obtained in that manner have better adsorbing and separating capabilities.
N-nonane is substantially inactive to the adsorbing characteristic of zeolite.
Adsorptive Selectivity of Component A relative to Component B, a (A/B) (RT for Component A) -(RT for n-nonane) (RT for Component B) -(F:T for n-nonane) The data obtained in this experiment are for the blank.
The condition for the measurement is shown in Table 1.
Table 1 Item Condition Amount of Adsorbing and about 10 g Separating Agent Flow Rate of m-xylene 120 cc/hr Pulse Sample n-C9 10 wt.%
2,4-DCT 18 wt.%
2,5-DCT 45 wt.%
2,6-DCT 27 wt.%
Amount 10 pl Temperature 150 C
Next, a mixture of m-xylene and dichlorotoluene that had been disoxidated through nitrogen bubbling and dewatered through a molecular sieve (this mixture had a dissolved oxygen content of nearly 0 ppm, as measured with a polarographic dissolved oxygen meter) was applied to the column. The amount of the mixture applied to the column was 520 times by weight the adsorbing and separating agent filled in the column. The liquid being flown out through the outlet of the column was sampled, and the adsorptive selectivity of the agent was determined in the same manner as above. The liquid flow condition in this experiment is shown in Table 2; and the flow rate-dependent adsorptive selectivity of the adsorbent tested herein is shown in Fig. 6.
Table 2 Item Condition WHSV (hr ) 64 Mixture Composition m-xylene 80 wt.%
2,4-DCT 4 wt.%
2,5-DCT 10 wt.%
2,6-DCT 6 wt.%
Temperature 150 C
Comparative Example 2:
The adsorptive selectivity f'or the blank was determined in the same manner as in Example 5. The same experiment as in Example 5 was repeated except that a mixture of m-xylene and dichlorotoluene that had been dewatered through a molecular sieve but not disoxidated through nitrogen bubbling (this mixture had a dissolved oxygen c(Dntent of nearly 40 ppm, as measured with a polarographic dissolved oxygen meter) was applied to the column, and the adsorption selectivity of the adsorbent was determined in the same manner as above. The flow rate-dependent adsorptive selectivity of the adsorbent tested herein is shown in Fig. 6.
B - A 100 - water content ABD (g/ml) = x (1-wherein;
A indicates the weight of the empty container (g), B indicates the weight of the sample ( adsorbent )+ A (g), and V indicates the volume of tY:ie measuring container (ml).
An adsorbent having a higher packing density is preferred, since its amount capable of being filled in a unit volume increases. However, an adsorben't having a too high packing density is unfavorable, since its adsorbing and separating capabilities for halogenated aromatic compounds are poor.
The porosity of an adsorbent: can be measured with ease, according to a method of mercury penetration, for which is used a porosimeter. Concretely, the porosity of the adsorbent of the invention is measured in the manner mentioned below.
The adsorbent to be measured is put in an electric furnace, calcined therein at 500 C for 2 hours, and then cooled in a desiccator to reach room temperature. This is put in a sample cell, and is thereafter filled with mercury in vacuum. Then, this is set in a porosimeter device. Pressure is applied thereto, whereupon the volume of miercury to be penetrated into the pores of the adsorbent grains is electrically detected.
Thus is obtained the relationship between the pressure Pm[psi]
and the pore volume[cc]. This measurement is repeated under different pressures. The pressure: Pm is converted into the pore radius, r, according to the following equation (1):
r = -2?'cos8/P --- (1) wherein;
r indicates the radius of pores into which mercury penetrates under a pressure P, [A], P indicates a pressure, P=Pm[psi]X6.89476X103[N/m-m], r indicates the surface tension of mercury, 0.484[N/m], and 0 indicates the contact angle of mercury to the sample (adsorbent), 141.'3[o ].
The volume of the adsorbent grains is obtained as follows:
The adsorbent grains to be measured are put into a sample cell.
The volume as expelled by the adsorbent grains to which is added mercury in vacuum, and the pore volume of the grains having a pore diameter of up to 3 um to w:hich is added mercury under pressure are summed up, and the total is the volume of the adsorbent grains. The pore volunie is the accumulated volume of mercury as penetrated into the qrains having a pore diameter of from 3}un to 10 nm. Accordingly, the porosity ( cc/cc ) of the adsorbent grains is defined as follows:
(pore volume (cc)) Porosity (cc/cc) = --- (2) (adsorbent g:rain volume (cc) Adsorbent grains having a larger porosity are preferred, since a halogenated aromatic compound could more easily diffuse inside the grains. However, too large grains are unfavorable, since the packing density of the adsorbent is lowered.
Preferably, the porosity of the adsorbent grains falls between 0.20 and 0.37 cc/cc, more preferably between 0.25 and 0.35 cc/cc.
The grain size of the adsorbent grains can be easily measured with a scale or a scale equ_Lpped with a magnifying glass.
At least any 10 adsorbent grains are measured for their grain size, and the data are averaged. The resulting mean value is the grain size of the grains. In the invention, the grain size of the adsorbent grains preferably falls between 0.1 and 1.0 mm, more preferably between 0.2 and 0.8 mm. Adsorbent grains having a smaller grain size are preferred, since the pathway in each grain through which the adsorbed molecules diffuse in the grains is shorter. However, too small grains are unfavorable, since they cause the increase in pressure loss, and since their industrial production is not economical.
The halogen to be in the halogenated aromatic compounds to which the invention is directed includesfluorine, chlorine, bromine and iodine. Of those, favorable to the invention are chlorine and bromine, and more favorable thereto is chlorine.
It is also desirable that the hal-ogenated aromatic compounds have at least one alkyl group. The alkyl group preferably has from 1 to 4 carbon atoms, and more preferred are methyl group, ethyl group and propyl group.
Specific examples of the ha]-ogenated aromatic compounds include fluorotoluene, chlorotoluene, bromotoluene, dichlorobenzene, dibromobenzene, fluorochlorobenzene, chlorobromobenzene, trichlorobenzene, dichlorofluorobenzene, dichlorobromobenzene, dibromochlorobenzene, dichlorotoluene, dibromotoluene, chloroxylene, bromoxylene, chloroethylbenzene, bromoethylbenzene, chlorocumene, chloropropylbenzene, bromocumene, bromopropylbenzene, chlorobutylbenzene, bromobutylbenzene, etc.
In the invention, when the dissolved oxygen content of the halogenated aromatic compound to be processed is not higher than 15 ppm by weight, the adsorbent used for the compound could be prevented from being deteriorated. Smaller dissolved oxygen content is better. Preferably, t:he dissolved oxygen content is at most 5 ppm by weight, more preferably at most 1 ppm by weight.
The dissolved oxygen conter.it of the aromatic compound could be measured with a Beckmari dissolved oxygen meter, a polarographic dissolved oxygen meter or the like.
To reduce the dissolved oxygen content of the aromatic compound to be at most 15 ppm by weight, for example, employable is any treatment of radiation, degassing, distillation, nitrogen sealing or the like.
In the invention, the radiation treatment is to contact a liquid of a dissolved oxygen-containing aromatic compound with an inert gas such as NZ or the like, thereby removing the dissolved oxygen from the aromatic compound. For the radiation, for example, NZ may be directly lbubbled into a liquid of an aromatic compound as put in a tank, or, alternatively, N2 may be contacted with a liquid of an aromatic compound in a countercurrent flow in a plate coJ-umn or a packed column. The pressure for the operation may be any of normal pressure, elevated pressure or reduced pressure. Regarding the temperature for the operation, the operation is generally effected at a temperature at which the aromatic compound to be processed could be in a liquid phase.
The degassing treatment includes, for example, a method of reducing the pressure in a tank as filled with a dissolved oxygen-containing aromatic compound, by the use a vacuum pump or the like; and a method of reducing the pressure in a plate column or a packed column as filled with a liquid of a dissolved oxygen-having aromatic compoundtothereby remove the dissolved oxygen from the compound. The pr-essure for the operation may be any of vacuum to normal pressure, but a lower pressure is preferred. Regarding the temperature for the operation, the operation is generally effected at a temperature at which the aromatic compound to be processed could be in a liquid phase.
The distillation treatment may be effected in any ordinary manner. For this, the distillation tower may be any of a plate column, a packed column or the like, and the pressure may be any of normal pressure, elevated pressure or reduced pressure.
The nitrogen sealing treatment is to put a dissolved oxygen-containing aromatic compound into a nitrogen-sealed container, for example, tank, before the compound is subjected to isomerization or adsorbing separation, so that the dissolved oxygen is removed from the compound through vapor-liquid equilibration.
If a halogenated aromatic compound to be subjected to adsorbing separation contains dissolved oxygen, the dissolved oxygen in the compound will form an oxygen-containing compound.
Since the resulting oxygen-containing compound has strong polarity, and is therefore strongly adsorbed by the adsorbing and separating agent, whereby tYae adsorbing and separating capabilities of the agent are much lowered. Therefore, reducing the dissolved oxygen content of the halogenated aromatic compound is effective for preventing the deterioration of the adsorbing and separating aclent, and it is believed that the regeneration cycle for the agent could thereby be prolonged.
The technique of adsorbing and separating a single isomer from a mixture of halogenated aromatic compound isomers according to the invention may be attained in so-called partitioning chromatography, in partitioning adsorption using a simulated-moving bed line comprising a series of partitioning chromatography columns. In the simulated-moving bed line, the most easily adsorbable substance is collected in the extract flow, while the most hardly adsorbable substance is collected in the raffinate flow.
The continuous adsorbing and separating technique using the simulated-moving bed line basically comprises adsorption, concentration, desorption and desorbent recovery, which are continuously repeated in that order. One example of a method of adsorbing and separating a mixture of chloroethylbenzene (hereinafter referred to as "CEB") isomers is mentioned below, in which m-CEB is adsorbed by the adsorbent used.
Fig. 2 shows a schematic view showing the adsorption and separation process according to the simulated-moving bed line. As in Fig. 2, adsorption chambers 1 to 12 all filled with an adsorbent are continuously connected with each other, through which the isomer mixture to be separated is circulated.
(1) Adsorption:
A mixture of CEB isomers from feed line 15 is contacted with an adsorbent, and a strongly adsorbable component, m-CEB is selectively adsorbed by the adsorbent, while the other weakly adsorbable components, o- and p-CEBs are recovered along with the desorbent in the form of a raffinate flow of raffinate line 16 that will be mentioned below.
(2) Concentration:
The adsorbent that has adsorbed the strongly adsorbable component, m-CEB is then contacted with a part of the extract that will be mentioned below, and the weakly adsorbable components remaining on the adsorbent are removed, whereby the strongly adsorbable component is concentrated.
(3) Desorption:
The adsorbent thus having the concentrated, strongly adsorbable component, m-CEB is contacted with a desorbent from desorption line 13, whereby the strongly adsorbable component is removed from the adsorbent, and recovered along with the desorbent in the form of an extract flow of extract line 14.
(4) Desorbent Recovery:
The adsorbent thus having adsorbed substantially only the desorbent is contacted with a part of the raffinate flow, and a part of the desorbent having been adsorbed by the adsorbent is recovered in the form of a desorbent recovery flow of desorption recovery line 17.
The adsorbing and separating operation for a halogenated aromatic compound is preferably effected in a liquid phase. A higher operation temperature is more preferred for higher diffusion rate of the compound being processed. Contrary to this, however, a lower operation temperature is more preferred for better adsorptive selectivity of the adsorbent used.
Because of the contradictory temperature-dependent factors, the operation temperature will be preferably between 50 and 2000 C.
EXAMPLES
Example 1:
1.2 kg (dry weight) of Na-X zeolite powder (from Toso) having a molar ratio SiOZ/A1z03 of 2.5, 0.96 kg of alumina sol ( from Nissan Chemical, having an A1203 content of 10 % by weight) and alumina gel (from Shokubai Kasei, having an A12O3 content of 75 % by weight) were mixed in a kneader (from Fuji Pawdal, Model KDHJ-10), and kneaded with a suitable amount of water added thereto, for about 1 hour. The resulting paste was extruded out through an extrude:r (from Fuji Pawdal, Model EXDS-60) equipped with a 0.3 mm-mesh screen, into pellets.
In order to round them and to increase their packing density, the resulting pellets were processed in a rounding machine (Marumerizer, Model QJ-230 from Fuji Pawdal), at a revolution of 850 rpm for 3 minutes.
Next, these were dried overnight at about 120 C. After having been dried, these were classified through a 80-mesh sieve to remove fine grains and through a 48-mesh sieve to remove coarse grains. The thus-classified grains were then calcined at 500 C for 2 hours.
The diameter of the adsorbent grains was measured with a scale equipped with a magnifying glass, and it was 0.3 mm. The length of the grains varied from about 0.3 mm to about 0.6 mm.
The packing density of the adsorbent was 0.54 g/ml. The pore volume of the adsorbent grains was measured, and the data are shown in Fig. 3. The adsorbent had a porosity of 0.27 cc/cc.
The adsorbent was filled into 12 columns each having a size of 4.6 mm~ x 1 m. Of those columns, four were set in a desorption zone, three were in a concentration zone, three were in an adsorption zone, and two were in a desorbent recovery zone in a simulated-moving bed line. A mixture of chloroethylbenzene ( CEB ) isomers was applied to the s_Lmulated-moving bed line, and the adsorbing and separating capabilities of the adsorbent in the line were checked. The starting CEB isomer mixture applied had a composition of o-CEB/m-CE13/p-CEB = 33/47/20. As the desorbent, used was xylene. The operation temperature was 130 C. The capabilities curve is shown in Fig. 4.
Comparative Example 1:
An adsorbent was prepared in the same manner as in Example 1, except that the extruded grains were not rounded with Marumerizer. The packing density of the adsorbent prepared herein was 0.49 g/ml. The pore volume of the adsorbent was measured, and the data are shown in Fig. 3. The adsorbent had a porosity of 0.38 cc/cc.
Using the adsorbent, the CEB isomer mixture was processed in the same manner as in Example 1 to check the adsorbing and separating capabilities of the adsorbent. The data obtained are shown in Fig. 4.
The data in Fig. 4 indicate that the most strongly adsorbable m-CEB was recovered in the extract flow and its purity in the flow was high. In addition, the data indicate that the adsorbent giving a higher ratio of m-CEB/ECEB (total of o-, m- and p-CEBs) in the extract flow and giving a lower ratio of m-CEB/FCEB in the raffineite flow has better adsorbing and separating capabilities. Obviously, it is known that the adsorbent having an increased packing density of 0. 54 mg/ml from 0.49 mg/ml and having a decreased porosity of 0.27 cc/cc from 0.38 cc/cc has better adsorbing ELnd separating capabilities.
Example 2:
An adsorbent paste was prepared in the same manner as in Example 1, except that Na-Y zeolite powder (from Toso) having a molar ratio Si02/A1Z03 of 5.5 was used herein, and this was extruded out through an extruder equipped with a 0.3 mm-mesh screen into adsorbent pellets.
In order to round them and to increase their packing density, the resulting pellets were processed in a rounding machine, Marumerizer, at a revolution of 850 rpm for 3 minutes.
Next, these were dried overriight at about 120 C. After having been dried, these were classified through a 80-mesh sieve to remove fine grains and through a 48-mesh sieve to remove coarse grains. The thus-classified grains were then calcined at 500 C for 2 hours.
The calcined grains were treated in an aqueous solution containing 5 % by weight of KNO3, at a liquid/solid ratio (L/S) of 4 ml/g at about 80 C for 1 hour. Next, these were washed with distilled water at a liquid/solid ratio of 4. The K ion exchanging treatment followed by washing with water was repeated 8 times. After this treatment, the grains were washed with distilled water at a liquid/solid ratio of 8, which was repeated 5 times.
Next, these grains were further subjected to ion exchanging treatment with an aqueous solution of 55 g of PbNO3 dissolved in one liter of water, at room temperature for about 1 hour, and then washed with distilled water at a liquid/solid ratio of 4. The washing was repe:ated 5 times.
The thus-prepared adsorbent was dried overnight at about 120 C, and then calcined at 500 c; for 2 hours.
The diameter of the adsorbent grains was measured with a scale equipped with a magnifying glass, and it was 0.3 mm. The length of the grains varied from about 0.3 mm to about 0.6 mm.
The packing density of the adsorbent was 0.65 g/ml. The pore diameter of the adsorbent grains was measured, and the data are shown in Fig. 3, which indicates the pore diameter distribution.
The adsorbent had a porosity of 0.26 cc/cc.
The adsorbent was filled inta 12 columns each having a size of 4. 6 mm~ x 1 m. Of those columns, four were set in a desorption zone, three were in a concentra"tion zone, three were in an adsorption zone, and two were in a desorbent recovery zone in a simulated-moving bed line. A mixture of dichlorobenzene (hereinafter referred to as "DCB") isomers was applied to the simulated-moving bed line, and the adsorbing and separating capabilities of the adsorbent in the line were checked. The starting DCB isomer mixture applied had a composition of o-DCB/m-DCB/p-DCB = 37/40/23. As the desorbent, used was dichlorotoluene. The operation temperature was 130 C. The capabilities curve is shown in Fig. 5.
Example 3:
An adsorbent was prepared in the same manner as in Example 2, except that the rounding treatment with Marumerizer was effected at a revolution of 400 rpin for 1 minutes. The packing density of the adsorbent was 0.60 (3/ml. The pore volume of the adsorbent grains was measured, and the data are shown in Fig.
3. The adsorbent had a porosity of 0.35 cc/cc.
The DCB adsorbing and separating capabilities of the adsorbent were checked in the samE; manner as in Example 2, and the data are shown in Fig. 5.
Example 4:
An adsorbent was prepared in the same manner as in Example 2, except that the extruder was equipped with a 1.2 mm-mesh screen and that a 24-mesh sieve and a 10-mesh sieve were used for the grain classification.
The diameter of the adsorbent grains was measured with a scale equipped with a magnifying glass, and it was 1. 2 mm. The length of the grains was 2.0 mm. The packing density of the adsorbent was 0.67 g/ml. The adsorbent had a porosity of 0.25 cc/cc.
The DCB adsorbing and separating capabilities of the adsorbent were checked in the same manner as in Example 2, and the data are shown in Fig. 5.
Fig. 5 indicates that the most weakly adsorbable m-DCB was recovered in the raffinate flow aizd its purity in the flow was high. In addition, the data in Fig. 5 indicate that the adsorbent giving a higher ratio of m-DCB/EDCB (total of o-, m-and p-DCBs) in the raffinate flow and giving a lower ratio of m-DCB/EDCB in the extract flow has better adsorbing and separating capabilities. Obviously, it is known that the adsorbents in Examples 2 and 3 have better adsorbing and separating capabilities.
Example 5:
An adsorbent for separating 2,4-dichlorotoluene (hereinafter referred to as DCT) was prepared according to the method of Example 3 in JP-A 5-70383. This adsorbing and separating agent is of X-type zeo:Lite containing, as cations, sodium and strontium ions. This was calcined at 500 C for 2 hours, and filled in a stainless steel column having an inner diameter of 4.6 mm and a length of 1 m. While m-xylene having been disoxidated through nitrogen bubbling (this m-xylene had a dissolved oxygen content of nearly 0 ppm, as measured with a polarographic dissolved oxygen meter) was introduced into the column at a constant flow rate, a small amount of a mixture of 2,4-, 2,5- and 2,6-DCTs and n-nonane that had been disoxidated in the same manner of nitrogen biubbling (this mixture had a dissolved oxygen content of nearly 0 ppm, as measured with a polarographic dissolved oxygen met:er) was applied to the column for an instant, and the liquid flowing out through the outlet was sampled at predetermined intervals, and analyzed for its composition through gas chromatography. All the starting liquid used herein were previously dewatered through a molecular sieve. Time-dependent]Ly plotting the data of the analysis gives the concentration;peak of each component. The selectivity of the adsorbing and. separating agent could be represented by the ratio of the difference in the retention time (hereinafter referred to as "RT") between one isomer and n-nonane to that in the same between another isomer and n-nonane, as in the equation mentioned below. In general, adsorbents having a larger value for the selectivity to be obtained in that manner have better adsorbing and separating capabilities.
N-nonane is substantially inactive to the adsorbing characteristic of zeolite.
Adsorptive Selectivity of Component A relative to Component B, a (A/B) (RT for Component A) -(RT for n-nonane) (RT for Component B) -(F:T for n-nonane) The data obtained in this experiment are for the blank.
The condition for the measurement is shown in Table 1.
Table 1 Item Condition Amount of Adsorbing and about 10 g Separating Agent Flow Rate of m-xylene 120 cc/hr Pulse Sample n-C9 10 wt.%
2,4-DCT 18 wt.%
2,5-DCT 45 wt.%
2,6-DCT 27 wt.%
Amount 10 pl Temperature 150 C
Next, a mixture of m-xylene and dichlorotoluene that had been disoxidated through nitrogen bubbling and dewatered through a molecular sieve (this mixture had a dissolved oxygen content of nearly 0 ppm, as measured with a polarographic dissolved oxygen meter) was applied to the column. The amount of the mixture applied to the column was 520 times by weight the adsorbing and separating agent filled in the column. The liquid being flown out through the outlet of the column was sampled, and the adsorptive selectivity of the agent was determined in the same manner as above. The liquid flow condition in this experiment is shown in Table 2; and the flow rate-dependent adsorptive selectivity of the adsorbent tested herein is shown in Fig. 6.
Table 2 Item Condition WHSV (hr ) 64 Mixture Composition m-xylene 80 wt.%
2,4-DCT 4 wt.%
2,5-DCT 10 wt.%
2,6-DCT 6 wt.%
Temperature 150 C
Comparative Example 2:
The adsorptive selectivity f'or the blank was determined in the same manner as in Example 5. The same experiment as in Example 5 was repeated except that a mixture of m-xylene and dichlorotoluene that had been dewatered through a molecular sieve but not disoxidated through nitrogen bubbling (this mixture had a dissolved oxygen c(Dntent of nearly 40 ppm, as measured with a polarographic dissolved oxygen meter) was applied to the column, and the adsorption selectivity of the adsorbent was determined in the same manner as above. The flow rate-dependent adsorptive selectivity of the adsorbent tested herein is shown in Fig. 6.
Claims (20)
1. An adsorbent for separating halogenated aromatic compounds, which comprises synthetic zeolite and has:
(i) a porosity of from 0.20 cc/cc to 0.37 cc/cc, (ii) a packing density of from 0.50 g/ml to 0.70 g/ml, and (iii) a grain size of from 0.1 mm to 1.0 mm.
(i) a porosity of from 0.20 cc/cc to 0.37 cc/cc, (ii) a packing density of from 0.50 g/ml to 0.70 g/ml, and (iii) a grain size of from 0.1 mm to 1.0 mm.
2. The adsorbent as claimed in claim 1, wherein the zeolite is faujasite-type zeolite.
3. The adsorbent as claimed in claim 1, wherein the zeolite is MFI-type zeolite.
4. The adsorbent as claimed in claim 1, wherein the zeolite is beta-type zeolite.
5. A method for separating halogenated aromatic compounds, which comprises contacting the adsorbent of any one of claims 1 to 4, with a mixture of halogenated aromatic compound isomers, to separate at least one halogenated aromatic compound isomer from the mixture.
6. A method for separating halogenated aromatic compounds, which comprises contacting the adsorbent of any one of claims 1 to 4, with a mixture of halogenated aromatic compound isomers having a dissolved oxygen content of at most 15 ppm by weight to thereby separate at least one halogenated aromatic compound isomer from the mixture.
7. The method as claimed in claim 6, wherein the halogenated aromatic compound isomer mixture is, prior to being contacted with the adsorbent, processed to remove the dissolved oxygen therefrom through any of radiation, degassing, distillation or nitrogen sealing.
8. The method as claimed in any one of claims 5 to 7, wherein the halogenated aromatic compound contains at least one chlorine.
9. The method as claimed in any one of claims 5 to 8, wherein the halogenated aromatic compound has at least one alkyl group.
10. The method as claimed in any one of claims 5 to 7, wherein the halogenated aromatic compound is fluorotoluene, chlorotoluene, bromotoluene, dichlorobenzene, dibromobenzene, fluorochlorobenzene, chlorobromobenzene, trichlorobenzene, dichlorofluorobenzene, dichlorobromobenzene, dibromochlorobenzene, dichlorotoluene, dibromotoluene, chloroxylene, bromoxylene, chloroethylbenzene, bromoethylbenzene, chlorocumene, chloropropylbenzene, bromocumene, bromopropylbenzene, chlorobutylbenzene, or bromobutylbenzene.
11. An adsorbent for separating at least one halogenated aromatic compound isomer from an isomer mixture thereof, which is a shaped calcined article made essentially of powdery synthetic zeolite and a binder, wherein the shaped article has:
a porosity of from 0.20 to 0.37 cc/cc, a packing density of from 0.50 to 0.70 g/ml, and a grain size of from 0.1 to 1.0 mm.
a porosity of from 0.20 to 0.37 cc/cc, a packing density of from 0.50 to 0.70 g/ml, and a grain size of from 0.1 to 1.0 mm.
12. The adsorbent as claimed in claim 11, wherein the binder is alumina, bentonite, kaolin or a mixture thereof and is contained in an amount of 5 to 40% by weight based on the shaped article.
13. The adsorbent as claimed in claim 11 or 12, wherein the synthetic zeolite is faujasite-type zeolite of the formula:
M2/n O.cndot.Al2O3.cndot.xSiO2.cndot.y H2O
wherein M is a metal ion or a hydrogen ion, n is the valence of M, x is a molar ratio of silica/alumina, and y is a degree of hydration.
M2/n O.cndot.Al2O3.cndot.xSiO2.cndot.y H2O
wherein M is a metal ion or a hydrogen ion, n is the valence of M, x is a molar ratio of silica/alumina, and y is a degree of hydration.
14. The adsorbent as claimed in claim 13, wherein M is an alkali metal or a hydrogen ion, n is 1, x is from 0.5 to 10.
15. The adsorbent as claimed in any one of claims 11 to 14, wherein the shaped calcined article is round pellets.
16. A method for separating at least one halogenated aromatic compound isomer from an isomer mixture thereof, which comprises contacting the isomer mixture having a dissolved oxygen content of at most 15 ppm by weight with the adsorbent as defined in any one of claims 11 to 15, to selectively adsorb a strongly adsorbable isomer with the adsorbent while recovering a weakly adsorbable isomer.
17. The method as claimed in claim 16, wherein the isomer mixture is a chloroethylbenzene (CEB) isomer mixture composed of m-CEB, o-CEB and p-CEB, whereby m-CEB is the strongly adsorbable isomer and o-CEB and p-CEB are the weakly adsorbable isomer.
18. A continuous method for separating at least one halogenated aromatic compound isomer from an isomer mixture thereof, which comprises:
(1) contacting the isomer mixture having a dissolved oxygen content of at most 15 ppm by weight with the adsorbent as defined in any one of claims 11 to 15, to adsorb a strongly adsorbable isomer with the adsorbent while recovering a part of a weakly adsorbable isomer as a raffinate flow;
(2) contacting the adsorbent after step (1) with an extract, to remove the weakly adsorbable isomer from the adsorbent while concentrating the strongly adsorbable isomer adsorbed with the adsorbent;
(3) contacting the adsorbent after step (2) with a desorbent, to remove the strongly adsorbable isomer from the adsorbent along the desorbent in the form of an extract flow;
and (4) contacting the adsorbent after step (3) with a part of the raffinate flow to recover the desorbent in the form of a desorbent recovery flow.
(1) contacting the isomer mixture having a dissolved oxygen content of at most 15 ppm by weight with the adsorbent as defined in any one of claims 11 to 15, to adsorb a strongly adsorbable isomer with the adsorbent while recovering a part of a weakly adsorbable isomer as a raffinate flow;
(2) contacting the adsorbent after step (1) with an extract, to remove the weakly adsorbable isomer from the adsorbent while concentrating the strongly adsorbable isomer adsorbed with the adsorbent;
(3) contacting the adsorbent after step (2) with a desorbent, to remove the strongly adsorbable isomer from the adsorbent along the desorbent in the form of an extract flow;
and (4) contacting the adsorbent after step (3) with a part of the raffinate flow to recover the desorbent in the form of a desorbent recovery flow.
19. The method as claimed in claim 18, wherein the isomer mixture is a chloroethylbenzene (CEB) isomer mixture composed of m-CEB, o-CEB and p-CEB, whereby m-CEB is the strongly adsorbable isomer and o-CEB and p-CEB are the weakly adsorbable isomer.
20. The method as claimed in claim 18 or 19, wherein the desorbent is xylene; and the method is operated at a temperature of 50 to 200°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10-97957 | 1998-04-09 | ||
| JP9795798 | 1998-04-09 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2268489A1 CA2268489A1 (en) | 1999-10-09 |
| CA2268489C true CA2268489C (en) | 2008-06-17 |
Family
ID=14206158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002268489A Expired - Lifetime CA2268489C (en) | 1998-04-09 | 1999-04-08 | Adsorbent for separating halogenated aromatic compounds and separation method using it |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US6320087B2 (en) |
| EP (1) | EP0948988B1 (en) |
| CA (1) | CA2268489C (en) |
| DE (1) | DE69922429T2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002147948A (en) * | 2000-11-10 | 2002-05-22 | Japan Organo Co Ltd | Gas separating device and method therefor |
| US7947978B2 (en) * | 2005-12-05 | 2011-05-24 | Megica Corporation | Semiconductor chip with bond area |
| EP2424270B1 (en) * | 2010-08-23 | 2014-05-21 | Knowles Electronics Asia PTE. Ltd. | Loudspeaker system with improved sound |
| EP3409837A1 (en) * | 2017-06-02 | 2018-12-05 | Benoit Pintat | An artificial turf infill material |
| US11453982B2 (en) | 2017-06-02 | 2022-09-27 | Benoit PINTAT | Artificial turf infill material |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2804203C3 (en) | 1978-02-01 | 1980-09-25 | Bayer Ag, 5090 Leverkusen | Process for the separation of isomeric dichlorotoluenes |
| JPS59122433A (en) | 1982-12-28 | 1984-07-14 | Toray Ind Inc | Separation and recovery of 3,5-xylenol |
| JPS62292736A (en) | 1986-06-13 | 1987-12-19 | Toray Ind Inc | Separation of aromatic halogen compound isomer |
| EP0322869B1 (en) | 1987-12-28 | 1992-09-09 | Toray Industries, Inc. | Process for separating dichlorocumene isomer |
| JP2659239B2 (en) * | 1989-05-02 | 1997-09-30 | パイオニア株式会社 | Light head |
| JPH0413639A (en) | 1990-05-08 | 1992-01-17 | Toray Ind Inc | Separation of 2,4-dichlorofluorobenzene |
| JPH09188638A (en) | 1996-01-10 | 1997-07-22 | Toray Ind Inc | Separation of dihalogenated benzene isomer |
-
1999
- 1999-04-06 US US09/287,044 patent/US6320087B2/en not_active Expired - Lifetime
- 1999-04-07 EP EP99302732A patent/EP0948988B1/en not_active Expired - Lifetime
- 1999-04-07 DE DE69922429T patent/DE69922429T2/en not_active Expired - Lifetime
- 1999-04-08 CA CA002268489A patent/CA2268489C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0948988B1 (en) | 2004-12-08 |
| CA2268489A1 (en) | 1999-10-09 |
| DE69922429D1 (en) | 2005-01-13 |
| DE69922429T2 (en) | 2005-12-01 |
| US20010007048A1 (en) | 2001-07-05 |
| EP0948988A1 (en) | 1999-10-13 |
| US6320087B2 (en) | 2001-11-20 |
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